A simple, accurate and inexpensive high performance liquid chromatography with electrochemical detection (HPLC-ECD) method for the simultaneous separation and determination of the three synthetic estrogens including diethylstilbestrol, dienestrol, and hexestrol in milk was established. For the sample treatment procedure, acetonitrile was added to the milk sample, the mixture was vortex mixed, centrifuged, concentrated by evaporation and determined by HPLC-ECD. The detection and quantification limits of the three estrogens obtained with ECD were lower than those obtained by diode array detection (DAD). Calibration curves, limit of detection and recoveries of diethylstilbestrol, dienestrol, and hexestrol with ECD ranged from 0.04 to 24 mg ml À1 , 4.7 Â 10 À3 to 7.1 Â 10 À3 mg ml À1 , and 83 to 103%, respectively. Meanwhile, the effect of thermal treatment on the stability of the estrogens was investigated, and the results showed that these compounds initially decreased by 26% for diethylstilbestrol, 32% for dienestrol, and 41% for hexestrol after five minutes of heat treatment, then remained stable with increasing duration of heat treatment. The method was applied to the determination of the three synthetic estrogens in authentic milk samples.
Aristolochia hainanensis
Merr. 1922, a well-known Chinese medicinal plant, is distributed in Hainan Province and Guangxi Province, China. In the current study, we sequenced the complete chloroplast genome of
A. hainanensis
. The complete plastome genome was 159,764 bp in length, with a GC content of 38.8%, showing a typical quadripartite organization. The genome contained a large single-copy (LSC) of 89,134 bp, a small single-copy (SSC) of 19,306 bp, and a pair of inverted repeats (IRs) of 25,662 bp. A total of 113 genes were annotated, including 79 protein-coding genes, 30 tRNAs, and four rRNAs. The
trnK
-UUU gene contained the longest intron (2644 bp). The topology of the maximum-likelihood tree supported a close relationship between
A. hainanensis
and
A. kwangsiensis
.
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